JPS6051336B2 - Interconnection line power change detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an interconnection line power change detection device for detecting abnormal sudden changes in interconnection line power due to causes in other systems in a power system that performs power interchange between two systems. It is something.

In the power system diagrams of FIGS. 1 to 4, the area within the diagonally shaded frame 1 is another power system, and the others are the main system. Shiya Katsuragi 152R in another system has an interconnection line with this system that is connected and disconnected, and although the upper bus bar of Shiya Katsuragi 152R is not shown in the diagram, many generator groups and load groups are connected to it. There is. The purpose of this system's line disconnection 152 is the same as that of other systems 152R, and it is for connecting and disconnecting interconnection lines between systems. Further, the generator G of the present invention is connected to the main system via the generator Shiya-ketsu 52 and the main transformer MT. Also, load group L is loaded and determined 52
It is connected to the main system via F and load transformer LT. Next, we will explain power interchange between this system and other systems.

The following four cases can be considered as methods. Case A; 1st
As shown in the figure, for the main system load L, the power of the generator G of the main system and the power shortage in the generator G are accommodated from other systems. Case B: As shown in FIG. 2, power is supplied from the generator G of the main system to the main system load L, and the surplus of the generator G is transferred to other systems. Case C: As shown in FIG. 3, while the generator G of the main system is stopped, power is supplied to the load L of the main system from another system.

Case D: As shown in FIG. 4, power from the main system generator G is supplied to other systems, but no power is supplied to the main system load L.

In the above-mentioned power interchange state, if the other system's power supply 152R is disconnected, in case A, the load that was being accommodated becomes insufficient and generator G is overloaded, causing the turbine rotation speed to drop. Since the turbine, generator, etc. may be in a dangerous state, increase the power generated by the generator G, or if the generator G cannot increase its output above the current value, change the load on the load side L to the output of the generator G. It will be necessary to reduce it to a reasonable value. In case B, the load that was being accommodated becomes surplus power, and the load on generator G becomes light, and the turbine rotation speed increases, potentially putting the turbine, generator, etc. in a dangerous state. If the output value of the generator G cannot be decreased below the current output value, it is necessary to increase the load L to a value commensurate with the output of the generator G. In case C, there is no particular effect on generator G. Furthermore, in case D, the load on the generator G becomes zero and the turbine rotational speed increases, so it is necessary to immediately stop the turbine and the generator. Conventionally, the trip of the shield breaker 152R is often determined based on the contact output of the shield breaker 152R itself. If the shield breaker 152R is located in a remote area other than the main system, the line resistance of the cable installed to bring the shield breaker contact into the main system will increase, so the transmission equipment may not be installed. need to be installed, which increases costs. Further, when a transmission device is provided, problems arise such as transmission delays and increased costs due to increased reliability of the transmission device or multiplexing of transmission lines to achieve high reliability. If all the contacts of the Yasushiya Disconnector 152R are used and the contacts cannot be put out.If there are many Yasiyaya Disconnectors 152R equivalent, and the contacts of each Shishaya Disconnector 152R cannot be put together in one place,
In addition, if the disconnector 152R is in another power company's system, the main system will be affected by an abnormality in the other system without making contact, and the main system will detect the abnormality in the other system. There are times when you have no choice but to do so. In addition, even if the contacts of other systems or disconnectors are connected, this system may also detect a trip of the other systems or disconnectors in order to improve reliability.
In order to solve the above problems, conventionally, zero power or zero current in the interconnection line with other systems is monitored using the X-rays shown in Figure 1, and when the interconnection line power is zero, the disconnector 152R trips (however, ,
It is locked so that power changes caused by turning on and off the shield disconnectors 152, 52, and 52F are not detected. ), however, the interconnection line power is not unidirectional, and because it is constantly accommodating from other systems to the main system and from the main system to other systems, the interconnection line power may temporarily become zero. In this case, false detection will occur. The present invention applies to power systems that are interconnected with other systems. Detects the power on/off or disconnection of interconnection lines installed in other systems based on the rate and amount of change in the interconnection line current or power in the own system, and detects connections from other systems. It is an object of the present invention to provide an interconnection line power change detection device that eliminates the need for interlocking trip contacts of disconnectors.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 5, the area within frame 1 is another power system, the others are the own system, and the area within frame 1 is an interconnection line current change detection circuit for realizing the present invention. In the other system power system in frame 1, the generator group and the load group are connected to the bus BUS, and the interconnection line power input,
It is connected to the disconnector 152R. A current transformer CT is provided on this interconnection line, and this rectifier CT secondary current 1 is inputted to a current change detection circuit 2. Like 152R, the cable disconnector 52 is a disconnector for connecting and disconnecting the interconnection line power, and when 152R is turned on, it is turned on, and when 152R is turned on, it is artificially disconnected.゜The generator G is turned off.
2 and the own system via the main transformer MT, and the own system is connected to the load group L of the own system via the load transformer LT and the load shear disconnector 52F. Current change detection circuit 2 detects interconnection line current 1
is input to the current/DC voltage transducer 22, which outputs an interconnection line current signal 1 which has a positive or negative polarity depending on the direction of the interconnection line current and is proportional to the amount of current.
Enter. The absolute value calculator 22 outputs a signal V2 having only an absolute value, regardless of the polarity of the signal V1 which changes depending on the direction of the interconnection line current, and inputs it to the voltage detector 23 and the change detector 24. Incidentally, since the absolute value calculator 22 is well known, it will not be particularly explained here. The voltage detector 23 operates when the interconnection line current is zero ampere, and the operation of the voltage detector 23 causes the auxiliary relay A to operate. Further, the change detector 24 is a sudden change detector of interconnection line current, and
, 52F is turned on or off, etc., when the rate of decrease in the absolute value of the interconnection line current is fast. It is also detected when the rate of change in current is small due to an increase in current, normal load fluctuations, generator output fluctuations, etc. Do not work. Further, the change detector 24 continues to operate only while the rate of decrease in the absolute value of the current is large, and becomes inoperative at the moment when the speed changes from high to low. When change detector 24 operates, auxiliary relay B operates. It should be noted that since there are conventionally many types of change detectors 24, such as those using a differentiator and a voltage detector, no particular explanation will be given here. Next, the relay sequence circuit will be explained with reference to FIG.

Contacts 152-1a, 152-2a, 152-3a are auxiliary contacts that close when the generator or disconnector 152 is "on," and contacts 52-1a, 52-3a are closed when the generator or disconnector 52 is "on." ”
The contact 52F-1b is an auxiliary contact that closes when the load is applied and the disconnector 52F is ``off''. 5
2F-2A and 52F-3a are auxiliary contacts that close when the load and disconnector 52F are turned on. The relay C edge and disconnector 152 are “on”, the generator and the disconnector 52 are “on”,
It operates when the load disconnector 52F is turned off and power is transferred from the generator G of the main system to other systems, and power is not being supplied to the main system load. Relay D edge and disconnector 152 is turned on, generator edge and disconnector 52 is turned off, and load liner and disconnector 52F is turned on to transfer power from other systems to main system load L. It operates when the generator in the grid is stopped.When the relay E or the disconnector 152 is turned on, the generator or the disconnector 52 is turned on, or when the load is applied or the disconnector 52F is turned on. It operates when power is supplied to the main system load L from both the other system and the main system generator G, or when the main system generator G is supplying power to the main system load L and the other system. The relays C, D,
When E operates, each relay contact C-1a, D-
1a and E-1a are closed. Contact F-1b is a hold reset push button switch. Contact B-1a is closed when relay B shown in FIG. 5 is operated. Relay G has a contact G- that closes when this relay G operates.
Self-maintaining due to 1a. Contact G-2a is closed when relay G is activated, and contact A-1b is opened when relay A shown in FIG. 5 is activated. HT is a time-limited operation relay, and the contact HT-1b is opened after the time-limited operation. Contact F-
2b is a hold reset push button switch similar to F-1b, which is opened only when a reset operation is performed.
Contact G-3a is closed when relay G is activated,
Contact A-2a is closed when relay A shown in FIG. 5 is in operation. Relay K is for the final output of the disconnector, and the contact F-
It operates when 2b, G-3a, and A-2a are closed, and self-maintains when contact K-1a is closed. Next, the operation of the above device will be explained. Fifth
In the figure, interconnection line current 1 is connected to current/DC voltage converter 21
It becomes a DC signal (1) which has positive or negative polarity depending on the direction of the interconnection line current and is proportional to the amount of interconnection line current.
The signal V1 is then input to the absolute value calculator 22. The output of the current/DC current converter 21 has two directions: the direction of interconnection line current, that is, power accommodation from the main system to other systems, and power accommodation from other systems to the main system, and depending on this direction, it can be positive or Since the output is of negative polarity, an absolute value calculator 22 is provided to facilitate subsequent calculations (current change detection). Then, the output V2 of the absolute value calculator 22 is input to the voltage detector 23, and this voltage detector 23 operates when the interconnection line current is zero ampere, and at this time, the relay A also operates, and the output V2 detects a change. The change detector 24 detects a sudden change and decrease in the interconnection line current 1, and operates the relay B accordingly. The operation of relays A and B will be explained with reference to FIG.

During the time interval, the interconnection line power 1 decreases at a certain rate of change, but this rate of change is sufficiently slower than the rate of change when the disconnector 152 trips, so the change detector 24 and relay B does not operate. Time again! Since the interconnection line current suddenly changes and decreases at times 1t2 and T7, the change detector 24 operates during the period of sudden change, but since the current has not reached zero ampere, relay A does not operate. Next, at time ζ, relay B operates because the current is changing in the same way as at time T7, and since the current is zero ampere at time ζ and TlO, at this time relay A is activated. Operate.

Furthermore, although the current increases rapidly at time 1, the change detector 24 does not detect any change in the increasing direction, so relay B is inoperative. And time, and Tl2
, relay B does not operate because the current changes slowly, but relay A does not operate because the current is approximately zero ampere during this period.
becomes the action. Next, in Fig. 6, relays C, D, E
represents the status of the three cases of the shield disconnectors 152, 52, and 52F in this system, and the three cases explained in the prior art (
1 or 2, 3, and 4). The reason for dividing the cases in this way is that the purpose of the present invention is to detect abnormal changes in interconnection line power due to causes in other systems, so even if a change in a disconnector in the main system causes the interconnection line current to become zero. This is to lock to prevent erroneous detection since the amperage or current may change suddenly. In any of the above three cases, the time shown in Figure 7! When the current suddenly changes and relay B operates and contact B-1a closes, relay G operates and contact J
G-1a is closed and relay G maintains itself.

At the same time, contact G-2a is closed, and since the interconnection line current is not zero ampere, relay A is inoperative and contact A-1b is closed, so timer HT counts the time. After a time count, contact T-1b is opened and relay G is inoperative. Timer HT is time T2
Or, as in the case of T7, when the current decreases temporarily, relay B operates and relay G self-holds, so it is provided to release the self-holding when the current is not zero ampere, and the timer is set to release the self-holding when the current suddenly changes. The time required for the interconnection line current to suddenly change from the maximum value to zero ampere is set to be greater than or equal to THT.
However, at time ζ or T9, the current suddenly changes, and at time T5, tlO, which is within timer THT, the current becomes zero ampere, so relays A and B operate and relay G
and relay K operates to maintain self-holding.

Then, the operation of relay K is announced to the operator, and relay G remains active until the operator operates the reset button and contacts F-1b and F-2b open.
and K continue to operate. When the sheath breaker 152 is tripped and the sheath breaker 152 is turned off, the relay G becomes inoperative, but there is no problem because the self-holding relay K does not become inoperable. In the above embodiments, changes in the interconnection line are detected only by the current, or a power/DC voltage converter (power converter) is used instead of the current/DC voltage converter to detect the interconnection line voltage and current. A similar effect can be obtained by a detection method using electric power input to this power converter.

Furthermore, in the above embodiment, the detection of the zero ampere current in the interconnection line is inputted to the output side of the absolute value calculator 22, but the point where the interconnection line current can be detected, for example, the input side of the absolute value calculator 22, is It may be detected by In addition, in the above embodiment, the detection point of the interconnection line current is detected between the shield disconnectors 152R and 152, but there are other points where the interconnection line current can be detected, for example, between the shield disconnectors 152R and 152.
2 and the connection point of the generator and load. In addition, although the above example describes the detection of interconnection line power or zero current, when only abnormal sudden changes in interconnection line power are to be detected, the interconnection line current or zero power detector and timer HT are excluded. Therefore, it can be easily detected. As described above, the present invention detects a sudden change and decrease state of the interconnection line current (or power) that occurs when the interconnection line current (or power) is tripped (or system abnormality), and also detects both the interconnection line current (or power) and zero. Detection is performed under the following conditions, so there is no malfunction, and there is no need to bring in contacts from other systems or disconnection trip contacts to the own system, eliminating the need for transmission equipment, resulting in an economical and highly reliable connection. A system line power change detection device can be provided.

[Brief Description of the Drawings] Figures 1 to 4 are interconnected power system diagrams showing interchangeable power by direction, and Figures 5 and 6 are system diagrams and relay sequence circuits showing one embodiment of the present invention. 7 are time charts showing the operation of the same embodiment. 1; Other systems, 152R, 152, 52, 52F; Strain breaker, CT; Current transformer, MT; Main transformer, G: Generator, L:
Load, LT; Load intensifier, 21; Current/DC voltage converter, 22; Absolute value calculator, 23; Voltage detector, 24; Change detector, A, B, C, D, E, F, G: Auxiliary relay, H
T: Time-limited relay.

Claims (1)

[Claims] 1. In a power system where power is mutually interchanged, a detector for detecting the amount of interconnection line power or current and a change detector for detecting the rate of change in interconnection line power or current is provided, and 1. An interconnection line power change detection device that detects an interconnection line breakage fault when the current becomes zero and the rate of change when the current becomes zero is abnormally large.